PROJECT SUMMARY/ABSTRACT Individuals with comorbid pain and depression ? particularly those who are treated with prescription opioid analgesics ? have a markedly increased risk of suicide, overdose and other opioid-related harms. Given the rising incidence of both suicide and drug overdose in recent years, there is an urgent need to address these intertwined national public health crises by identifying effective strategies to prevent suicide and other opioid- related harms, particularly for vulnerable populations with comorbid pain and depression. Improving access to depression treatment is one strategy that may hold promise: depression is commonly underdiagnosed and undertreated in individuals with pain, despite the fact that effective pharmacologic and non-pharmacologic treatments exist and can improve both pain and mood symptoms. There is a paucity of evidence, however, on the impact of depression treatments on suicide and overdose among patients who are treated with opioid analgesics. The goals of our current NIDA-funded R01, ?The Opioid Crisis: The Effects and Unintended Consequences of State Policies on Opioid Analgesic Prescribing,? include examining the relationship between opioid prescribing patterns and adverse patient outcomes. In this administrative supplement we will extend this work to examine outcomes for the understudied yet high-risk subpopulation of patients with chronic pain who may have unrecognized depression, and to assess the role of depression treatment as a potential mediating factor in the relationship between opioid use and opioid-related harms including suicide. Our specific aims are as follows. First, we will examine the relationship between county-level prescribing rates for opioid analgesics and antidepressants, and suicide and overdose rates over time. Second, using individual- level commercial claims data, we will examine the association between pharmacologic and non-pharmacologic treatments for depression, and overdose, intentional self-harm and other opioid-related harms among patients treated with prescription opioids in individual-level analyses. We will also assess for possible heterogeneous effects according to patients' clinical and demographic characteristics, the quality of depression treatment, opioid prescribing patterns and other contextual factors. This research will advance the parent R01's goal of strengthening our response to the public health crises of opioid misuse, overdose and suicide.